Stacking mechanism



Nov. 6, 1962 w. HANSTEIN ETAL 3,062,537

STACKING MECHANISM 2 Sheets-Sheet 1 Filed May 25, 1959 INVENTORS WALTER HANSTEIN BY THOMAS J. McKNlGHT AIIORNEY Nov. 6, 1962 Filed May 25, 1959 W. HANSTEIN ETAL STACKING MECHANISM 2 Sheets-Sheet 2 IN V EN TORS WALTER HANSTEIN THOMAS J. MCKNIGHT ATTORNEY United States Patent Ofifice 3,062,537 Patented Nov. 6, 1962 3,062,537 STACKING MECHANISM Walter Hanstein, Villanova, and Thomas J. McKnight, Paoli, Pa., assignors to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed May 25, 1959, Ser. No. 815,430 15 Claims. (Cl. 271-71) This invention relates generally to sheet feeding machines and more particularly to devices for stacking sheet material in a receptacle or stacking bin. While not limited to high speed operation, the invention finds special application in business machines for rapid stacking of paper bank checks, punch cards and the like following various operations on or with respect to such sheet items.

In the operation of stacking record sheet material such as bank checks, many times it is important that the sheets be stacked sequentially in order to preserve the original order of the sheets. In this respect, prior art stacking devices have been open to certain objections. For example, some devices stack the sheets on-the-fly by permitting the sheets to drop into a receptacle or upon a spring-loaded plateform. The disadvantage with this type of stacker, particularly when stacking at high speeds, is the possibility of stacking sheets out of order; that is, a sheet deposited for stacking may fall in ahead of the previously stacked sheet rather than behind it and thus destroy the desired order arrangement.

Still other stacking devices utilize a rotary drum with grippers. This type of device must generally be brought to a stop before the gripping cycle commences, and accordingly, is accompanied by an increase in stacking time. Furthermore, it must be accurately timed and synchronized with the movement of the sheet, however, even with precision arrangements, the sheets do occasionally overshoot the grippers, resulting in misfeeds.

An object of the invention is to provide an improved sheet stacking device.

Another object of the invention is to provide a sheet stacker which will stack sheets in the order in which received without the possibility of a sheet being stacked out of order.

A further object of the invention is to provide apparatus for stacking sheet materal which aifords a positive entry of the sheets into the sheet gripping or holding elements of the stacker without the possibility of a sheet over-shooting or missing such elements.

Still a further object of the invention is to provide a sheet stacker which will receive a moving sheet and deposit the sheet in a stacking bin without stopping movement of the sheet during transit.

Another object of the invention is to provide an asynchronous stacking device under control of a moving sheet, thereby eliminating timing requirements of the stacker relative to movement of the sheet.

A further object of the invention is to provide a sheet stacking apparatus which will maintain the lateral position of sheets received for stacking such as sheets that have been offset for special handling, counting and the like, and deposit the sheets in a suitable stacking bin in their offset position.

FIG. 1 with the stacking drum in a stationary condition;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 illustrates various conditions of the apparatus during a stacking operation;

FIG. 5 is an enlarged detail of a fragmentary portion of certain of the stacker drum members; and

FIG. 6 is a detail of a portion of the apparatus shown in FIG. 3.

Considered briefly, the invention comprehends the use of a normally stationary stacking drum with means for feeding a sheet along the periphery of the drum to a predetermined position. At this position, means are provided to detect the presence of the sheet and initiate a rotary movement of the drum for stacking the sheet in a suitable bin or receptacle. Means are provided which cooperate with the drum for holding the sheet thereto during rotation of the drum.

Referring to the drawings and particularly to FIG. 1, the apparatus is supported in a frame-work comprising side plates 19 and 11 having rearwardly extending portions 12 and 13 which form the side walls of a stacking bin 14. A sheet stack back-up member 15 (FIG. 2) is secured to spaced rods 16 and 17 which pass freely through holes in the end wall 13 of the stacking bin and are connected by means of a bridge plate 19. The back-up member 15 is urged leftwardly as seen in FIG. 2 by means of tension spring Zil and 21 secured at one end to bridge plate 19 and at the other end to fixed pins 22 and 23.

A stacking drum 24 (FIG. 3) is illustrated in one form as a plurality of circular discs 25 and 26 secured to a disc shaft 27 mounted in anti-friction hearings in the side plates 10 and 11. The discs 25 and 26 extend freely into slots 28 (FIG. 2) formed in the floor 29 of stacking bin 14.

The two thickest discs 25 are each provided with a pair of elongated flexible spring leaves 30, each secured at one end as seen most clearly in FIG. 5, to a notchedout peripheral portion of the respective disc 25. The secured ends of the spring leaves are in diametrically opposite positions on discs 25 and their free ends tend to flex away from the discs to assume a position tangent thereto but for the most part are constrained against so doing as will be explained hereinafter.

Discs 26 are provided with diametrically opposite peripheral nesting notches 26a (FIG. 1) which are in axial alignment with nesting notches 25a (FIG. 5) formed by spacers 32 and flats 33 formed on discs 25. The notches 25a and 26a serve as sheet stops under certain conditions, as will be explained hereinafter.

Associated with discs 25 are pressure rollers 34 and 35 (FIG. 1) rotatably mounted respectively on shafts 36 and 37 which pass freely at their end portions through elongated slots 38 (FIG. 2) in side plates 10 and 11 and are secured at their outer ends to links 39 and 40. The pressure rollers are biased against discs 25 by tension springs 41 and 42 secured respectively to links 39 and 40 and fixed pins 43 and 44.

A drive shaft 45 mounted in anti-friction hearings in side plates 10 and 11 is operated from a source of power such as an electric motor, not shown, by means of a belt 46 engaged about a pulley 47 (FIG. 3) fixed on the drive shaft 45. Motion is transmitted from drive shaft 45 to a shaft 48 by means of pulleys 49 and 50 fixed respectively on shaft 45 and 48 and a belt 5-1. Shaft 48 is similarly mounted as shaft 45 in anti-friction hearings in side plates 10 and 11.

Secured on drive shaft 45 and opposite respective spaces 52 and 53 (FIG. 3) between a disc 25 and a disc 26 are feed rollers 54. Similarly disposed with respect to spaces 52 and 53 are forwarding rollers 55 (FIG. 2) secured on 26. .radiation from lamp bulb 74, photosensitive element 73 shaft 48. Pressure rollers 56 and 57 cooperating with feed rollers 54 and forwarding rollers 55 respectively, are mounted on rock arms 58 pivotally connected on pins .59 secured to slides 60, the slides having limited movement along their length by means of elongated slots 61 therein slidably received on pins 62 secured to fixed plates 63. The disc shaft 27 passes through clearance holes 64, and 65 (FIG. 3) in plates 63 and slides 60 respectively, the clearance holes 65 being sufiiciently large to allow the slides 69 their limited movement mentioned above.

The pressure rollers 56 and 57 are biased into contact with the feed rollers 54 and forwarding rollers 55 respectively, by means of tension prings 66 secured at one end to lateral cars 67 of slides 60, and at their other ends to crank-shaped fittings 68 having hub portions 69 freely mounted on disc shaft 27.

The feed rollers 54 and forwarding rollers 55 project through suitable clearance apertures in an arcuately shaped member 70 (FIG. 2) secured at its upper end to a frame cross-member 71 and at its lower end to the underside of an in-feed platform 72.

As will be explained more fully hereinafter, there is provided a device adjacent the path of sheet feeding and actuated by a moving sheet for initiating a rotative movement of drum 24. Such a device may take a variety of forms but, as illustrated in FIG. 2, preferably comprises a photo-sensitive element 73 secured to cross-member '71 and exposed to a source of radiation such as a lamp bulb 74 secured to a plate 63.

The disc shaft 27 may be rotated through various angular increments as desired, depending upon the particular stacking requirements, but is preferably rotated a half revolution for each stacking operation. Accordingly, there is provided a suitable clutch mechanism 76 (FIG. 3) which, in one form as illustrated, is a singlerevolution type comprising a driving disc 77 secured on drive shaft 45 and a driven disc '78 slidably keyed on a clutch shaft 79 and urged into frictional engagement with the driving disc 77 by a compression spring 80. The clutch shaft 79 is coupled to disc shaft 27 by suitable transmission means which, as illustrated, comprises in one form a gear 81 secured on clutch shaft 79 in mesh with gear 82 secured on disc shaft 27, the gears 81 and 82 being in the ratio of 1:2.

Associated with clutch 76 are an electromagnet 83 (FIGS. 3 and 6) secured to a fixed bracket 86 and an armature 84 pivotally mounted at 85 on bracket 86. A

tension spring 87 secured to a lug 89 on bracket 86 and the lower end of armature 84 (FIG. 6) urges the upper upper end of the armature into a peripheral notch 88 in driven disc78 to normally block the disc against rotation.

In the operation of the apparatus, disc shaft 27 is initially stationary while drive shaft 45, shaft 48, feed rollers 54 and forwarding rollers 55 are rotating con- .spring leaves 30 reside freely at their lower portions in slots 28 and flexed against the sheet stack S.

A sheet S1 to be stacked (FIG. 4a) is fed to the apparatus along platform 72 by sheet delivery means, not shown, until it is engaged by feed rollers 54 and advanced through throats 75 to forwarding rollers 55 which further advance the sheet along the throats around the discs 25 and When the leading edge of the sheet intercepts the will cause energization of electromagnet 83 by means of suitable circuitry which, in one form, comprises an amplifier, a pulse shaper and a power amplifier all of which may be of well known design, but here illustrated schematically in FIG. 3 by block 96). Energization of electro-magnet 83 will cause it to attract armature 84 thereby to release the driven disc 78 to the torque of driving disc 77, and accordingly cause rotation of disc shaft 27.

The timing is such that clutch 76 will engage approximately at the time the leading edge of sheet S1 reaches the nesting notches a and 26a (FIG. 4b). As the disc shaft 27 commences to rotate, rollers 34 and will exert pressure against the spring leaves 30 which in turn will press and hold the sheet S1 to the periphery of discs 25 (FIG. When the leading edge of the sheet arrives at the top of the stacking bin floor 2h shortly before the completion of a half revolution of disc shaft 27, the free ends of spring leaves 3t) will just have passed from beneath the upper pressure rollers 34 thereby allowing the spring leaves to flex toward the pile of stacked sheets S (FIG. 4a) and press the previously stacked sheet S2 against the stack. The sheet S1 will be stripped from the discs 25 and spring leaves 36 by the floor 29 and deposited thereon in the position previously occupied by sheet S2. The disc shaft 27 is brought to a stop shortly thereafter after completing a half revolution, as seen in FIG. 4:), with spring leaves 36 disposed between sheets S1 and S2. The opposite pair of spring leaves which Were in the uppermost position at the start of the operation are now in the lower position and the apparatus is again in condition for the next stacking operation.

Disc shaft 27 is stopped after a half revolution, as mentioned above, by releasing armature 84 to engage notch 88 on driven disc 78. This is accomplished by deenergization of electromagnet 33 when the trailing edge of the sheet has passed from between the photosensitive element 73 and lamp bulb 74.

The spacing between the feed rollers 54 and forwarding rollers is somewhat less than the length of the sheet being handled and therefore in order to avoid any buckling of the sheet when it reaches the forwarding rollers, the latter are rotated at a higher tangential velocity than the feed rollers. This, of course, places the sheet in tension while it is engaged by both the feed rollers and forwarding rollers, and therefore it is preferable to construct the forwarding rollers of a low friction material, such as nylon for example, lower than the friction of the feed rollers to allow the forwarding rollers to slide sufficiently on the sheet when it is in tension to prevent tearing it.

In the stationary condition of disc shaft 27, the spacing between the forwarding rollers 55 and nesting notches 25a and 26a in the sheet receiving position is likewise somewhat less than the length of the sheet so that in this area also, in certain situations, slidability of the forwarding rollers on the sheet prevents buckling the sheet against the nesting notches. Such a situation might occur, for example, if the sheet were skewed when it reached the nesting notches resulting in a later triggering of the photosensitive element 73, or in the event the photosensitive element or clutch failed to operate. In the latter situation, the nesting notches will stop movement of the sheet while the forwarding rollers slide on it. Thus the sheet is preserved against any possible damage until the defective condition can be remedied.

Slidability of the forwarding rollers on the sheet is also preferable where it is desired to rotate the discs at varying tangential velocities, such as in cycloidal motion, for example, relative to a constant tangential velocity of the forwarding rollers. In such case, slida-bility of the forwarding rollers would prevent both buckling and tearing of the sheet.

While there has been disclosed a specific embodiment of the invention, it is to be understood that this is the preferred form exemplary of the principles of the invention, and that the invention may be constructed in a variety of modifications and arrangements without depart! ing from the true spirit and scope thereof. Accordingly, it is to be understood that the invention is not to be limited by the specific structure disclosed but only by the subjoined claims.

What is claimed is:

1. In a sheet stacking mechanism, the combination comprising, a rotatable drum, sheet stop means on the drum,

an elongated leaf member secured at one end to said drum with its free portion forming a throat with the periphery of the drum when the latter is stationary, said throat extending to said stop means, roller means including a f rwarding roller for advancing a sheet along said throat toward said stop means, said roller means being spaced from the stop means a distance somewhat less than the length of said sheet when said drum is stationary, means adjacent the path of sheet feeding and actuated by said sheet for initiating rotation of said drum as the sheet arrives at the stop means, said forwarding roller having a coefiicient of friction with respect to said sheet which will allow it to slip thereon in the event the sheet reaches the stop means before said drum is rotated, and means for pressing the free portion of the leaf member against the sheet and the sheet against the drum periphery when the drum is ID- tated.

2. In a sheet stacking mechanism, the combination of a rotatable drum, an elongated spring leaf secured at one end to said drum with its free portion forming a throat with the periphery of the drum when the latter is stationary, first roller means including a feed roller for advancing a sheet along said periphery and throat, second roller means including a forwarding roller for further advancing the sheet along the periphery and throat, said second roller means being spaced from the first roller means a distance somewhat less than the length of said sheet, said forwarding roller being operable at a higher tangential velocity than said feed roller, one of said last mentioned rollers having a lower coefficient of friction with respect to said sheet than the other roller and which will allow it to slip somewhat on the sheet when the Sheet is tensionally gripped by the first and second roller means, and means for pressing the free portion of the spring leaf against the sheet and the sheet against the periphery 'of the drum when the drum is rotated.

3. In a sheet stacking mechanism, the combination of a rotatable drum, an elongated spring leaf secured at one end to said drum with its free portion forming a throat with the periphery of the drum when the latter is stationary, first roller means including a feed roller for advancing a sheet along said periphery and throat, second roller means including a forwarding roller for further advancing the sheet along the periphery and throat, said second roller means being spaced from the first roller means a distance somewhat less than the length of said sheet, said forwarding roller being operable at a higher tangential velocity than said feed roller, one of said last mentioned rollers having a lower coefficient of friction with respect to said sheet than the other roller and which will allow it to slip somewhat on the sheet when the sheet is tensionally gripped by said first and second roller means, means adjacent the path of sheet feeding actuated by said sheet for initiating rotation of said drum, and means for pressing the free portion of the spring leaf against the sheet and the sheet against the drum periphery when the drum is rotated.

4. A sheet stacking mechanism comprising, a rotatable drum constructed of a plurality of spaced apart disc members each having a peripheral notch, said notches being in axial alignment, a plurality of elongated spring leaves each secured at one end to a disc member with their free portions forming throats with the peripheries of their respective disc members when said drum is stationary, said throats terminating at the respective notches, roller means including a forwarding roller for advancing a sheet along said throat toward said notches, said roller means being spaced from said notches a distance somewhat less than. the length of said sheet when said drum is stationary, means adjacent the path of sheet feeding and actuated by said sheet for initiating rotation of said drum as the sheet arrives at said notches, said forwarding roller having a coeflicient of friction with respect to said sheet which will allow it to slip thereon in the event the sheet reaches said notches before said drum is rotated, means for pressing the free portions of the spring leaves against the sheet and the sheet against the peripheries of their respective discs when the drum is rotated, and means for stripping the sheet from the disc members and spring leaves.

5. A sheet stacking mechanism comprising, a stacking drum rotatable in angular increments of a revolution, a plurality of elongated leaf members each secured at one end to said drum, a plurality of sheet stop means on said drum each associated with one of said leaf members, each leaf member and its associated stop means being operative during one of said increments of rotation to cooperate with the drum for controlling movement of a sheet received for stacking, the free portion of the operative leaf member forming a throat with the periphery of the drum when the latter is stationary, roller means including a forwarding roller for advancing said sheet along said throat toward the operative stop means, said roller means being spaced from the operative stop means a distance somewhat less than the length of said sheet when the drum is stationary, means adjacent the path of sheet feeding and actuated by said sheet for initiating an increment of rotation of said drum as the sheet arrives at the operative stop means, said forwarding roller having a coefficicnt of friction with respect to said sheet which will allow it to slip thereon in the event the sheet reaches the operative stop means before said drum is rotated, and means for pressing the free portion of the operative leaf member, against the sheet and the sheet against the drum periphery when the drum is rotated.

6. A sheet stacking mechanism as defined in claim 5 wherein said plurality of leaf members comprises leaf members arranged at two diametrically opposite positions on said drum, and said plurality of stop means comprises a like number similarly arranged on the drum, and wherein said angular increments are each a half revolution.

7. A sheet stacking mechanism as defined in claim 6 and including means for stripping the sheet from the drum and operative leaf member.

8. A sheet stacking mechanism comprising, a rotatable drum constructed of a plurality of spaced apart disc members each having a peripheral notch, said notches being in axial alignment, a plurality of elongated spring leaves each secured at one end to a disc member with their free portions forming throats with the peripheries of their respective disc members when said drum is stationary, said throats terminating at the respective notches, first roller means including a feed roller for advancing a sheet along said peripheries and throats, second roller means including a forwarding roller for further advancing the sheet along said peripheries and throats, said second roller means being spaced from the first roller means a distance somewhat less than the length of said sheet, said forwarding roller being operable at a higher tangential velocity than said feed roller, one of said last mentioned rollers having a lower coelficient of friction with respect to said sheet than the other roller and which will allow it to slip somewhat on the sheet when the sheet is tensionally gripped by said first and second roller means, means adjacent the path of sheet feeding and actuated by said sheet for initiating rotation of said drum as the sheet arrives at said notches, said forwarding roller having a coefficient of friction with respect to said sheet which will allow it to slip thereon in the event the sheet reaches said notches before said drum is rotated, and means for pressing the free portions of the spring leaves against the sheet and the sheet against the peripheries of their respective discs when the drum is rotated.

9. A sheet stacking mechanism as defined in claim 8 characterized further in that said forwarding roller has a lower coeflicient of friction with respect to said sheet than said feed roller.

10. A sheet stacking mechanism as defined in claim 8 characterized further in that said means for initiating rotation of said drum includes an element sensitive to radiation.

11. A sheet stacking mechanism as defined in claim 8 characterized further in that said forwarding roller has a lower coeflicient of friction with respect to said sheet than said feed roller and said means for initiating rotation of said drum includes an element sensitive to radiation.

12. In a sheet stacking mechanism, the combination comprising, a stacking drum rotatable in angular increments of a revolution, a plurality of elongated flexible leaf members each secured at one end to said drum with its free portion radially spaced from the periphery of the drum when the drum is stationary, each said free portion having a length suitable for embracing a sheet along substantially its full length, and normally stationary roller means arranged to rotate on the external surfaces of said leaf members from said secured ends toward said free portions for causing said free portions to wrap about a sheet and the sheet to wrap about the periphery of said drum when the drum is rotated.

13. In a sheet stacking mechanism, the combination of a rotatable drum, an elongated flexible leaf member secured at one end to said drum with its free portion radially spaced from and forming a throat with the periphery of the drum when the latter is stationary, said free portion having a length .suitable for embracing a sheet along substantially its full length, means for feeding a sheet along said throat and along said periphery until the sheet is substantially within the end limits of said free portion, means adjacent the path of sheet feeding and actuated by said sheet for initiating rotation of said drum, roller means rotated by rotation of said drum and in the path of movement of said free portion for causing said free portion to wrap about said sheet and the sheet to wrap about the periphery of said drum when the drum is rotated, and

means for stripping the sheet from the drum and leaf member.

14. A sheet stacking mechanism comprising, a rotatable drum constructed of a plurality of spaced apart disc members, a plurality of elongated flexible spring leaves each secured at one end to a disc member with its free portion radially spaced from and forming a throat with the periphery of its respective disc member when the drum is stationary, each said free portion having a length suitable for embracing a sheet along substantially its full length, means for feeding a sheet into said throats and along the peripheries of said disc members until the sheet is substantially Within the end limits of each said free portion, means adjacent the path of sheet feeding and actuated by said sheet for initiating rotation of said drum, and a plurailty of spring pressed rollers each in substantial contact with the periphery of a disc member causing said free portions to wrap about said sheet and the sheet to wrap about the peripheries of said dics members when the drum is rotated.

15. A sheet stacking mechanism according to claim 14 characterized further in that the means for initiating rotation of the drum includes an element sensitive to radiation.

References Cited in the file of this patent UNITED STATES PATENTS 1,560,536 Christopherson Nov. 10, 1925 2,026,162 De Manna Dec. 31, 1935 2,095,498 Hanauer Oct. 12, 1937 2,794,637 Rugg June 4, 1957 2,903,965 Eichenbaum etal. Sept. 15, 1959 

